This invention relates to a series of bicyclic imidazole or imidazoline derivatives having ectoparasiticidal, especially insecticidal (particularly against blowfly larvae) and acaricidal (including miticidal), and anthelmintic activity.
Eggs are laid by the adult female insects on animal skins, and the larvae produced tend to burrow into the skins of the afflicted animals and thereby spoil the state of the skins, with the consequence, for example, that cattle hides and sheep skins and fleece intended for the manufacture of leather, sheepskin and woollen goods, respectively, are reduced in quality. Furthermore, the state of health and quality of the flesh of afflicted animals may be detrimentally affected. Certain insect larvae, for example, the larvae of blowflies which tend to live in sheep skin, are capable of bringing premature death to the animal if present in sufficient abundance.
British Patent Specification No. 1,404,708 to Rhone-Poulenc S. A. discloses some of the compounds of the present invention, as hereinafter described in formula (I), but only as psychic energizers and antidepressants having anorexigenic properties. In detail, this specification discloses compounds of the formula: ##STR1## where R represents a phenyl radical unsubstituted or substituted by 1 or 2 atoms or radicals, which--when 2 substituents are present--may be the same or different, selected from halogen atoms and alkyl, alkoxy, alkylthio, dialkylamino, dialkylsulphamoyl, nitro, cyano and trifluoromethyl radicals, or R represents a 2-, 3- or 4-pyridyl radical unsubstituted or substituted by an alkyl or alkoxy radical, the alkyl containing radicals and alkyl moieties of the other radicals containing 1 to 4 carbon atoms, and acid addition salts thereof. The specification states that the compounds of outstanding interest are those wherein R is a phenyl radical or a phenyl radical substituted, preferably in the 3-position, by a halogen atom or an alkyl (preferably methyl) radical, an alkoxy (preferably methoxy) radical, an alkylthio (preferably methylthio) radical, or a nitro or trifluoromethyl radical, and acid addition salts thereof. In all the specific Examples to compounds where R is substituted phenyl, there is either a single substituent in the 3- or 4-position, or, in the case of Example 5, there are 2 substituents, namely chloro in the 3- and 5-positions.
This reference contains no reference to, nor any specific Examples to, compounds where R is a phenyl radical substituted in the 2-position. On the other hand, we have found that compounds of the formula (I), as hereinafter described, in which the benzene ring contains a substituent in the 2-position and optionally, a further substituent or substituents, are especially useful as insecticides, acaricides and anthelmintics and are the preferred compounds of the formula (I) as hereinafter described for this purpose.
In addition, British Patent Specification No. 1,180,202 (Rhone-Poulenc S. A.) discloses compounds of the formula: ##STR2## where R.sub.1 is hydrogen or phenyl, R.sub.2 is hydrogen or methyl and R.sub.3 is hydrogen, phenyl or hydroxyphenyl, and their acid addition salts, but only as anti-viral agents.